Insights derived from a combination of genetic and biochemical approaches have resulted in significant advances in our understanding protein-protein interactions and protein-nucleic acid interactions, especially in viral systems. The processes of viral assembly and genome encapsidation provide ideal targets for antiviral therapeutics as they are unique to the virus, thus agents directed against these steps in the viral life cycle are less likely to be toxic to the host. The focus of this proposal is on the proteins implicated in HSV-1 genome encapsidation, specifically UL6: the putative portal protein. In this investigation, second-site suppressors of UL6 temperature sensitive (ts) mutants will be used to genetically define interactions between UL6 and the procapsid as well as other cleavage/packaging proteins. Ideally, these studies, combined with biochemical and structural analyses performed by others, will ultimately lead to new information about the use of these viral molecules as targets for viral inhibitors.